WO2010112772A2

WO2010112772A2 - Viscosity-reducing super-plasticising copolymers

Info

Publication number: WO2010112772A2
Application number: PCT/FR2010/050611
Authority: WO
Inventors: David Rinaldi; Horacio Naranjo; Martin Mosquet; Philippe Maitrasse; Alexandre Desseroir
Original assignee: Lafarge; Chryso
Priority date: 2009-04-01
Filing date: 2010-03-31
Publication date: 2010-10-07
Also published as: ZA201107196B; CN102421721A; CN102421721B; MY151185A; ES2534110T3; FR2944009A1; US20120095134A1; CA2757024C; PL2414302T3; FR2944009B1; BRPI1006743A2; EP2414302B1; BRPI1006743A8; MA33879B1; CA2757024A1; US8563631B2; EP2414302A2; WO2010112772A3

Abstract

The invention mainly relates to the use of a (co)polymer having a main chain essentially consisting of (meth)acrylic units and polyoxyalkylated side-chains containing statistically-distributed hydrophobic units as an adjuvant for lowering the viscosity of hydraulic compositions.

Description

SUPERPLASTIVE COPOLYMERS VISCOSITY REDUCERS

The present invention relates to the use of specific polyalkoxylated polycarboxylic (co) polymers for improving the viscosity of hydraulic compositions.

When placing a fluid concrete on site, an important performance criterion is the viscosity of the concrete. A low viscosity is useful because it speeds up the preparation, transfer and placement. It is particularly sought after for self-leveling concrete formulations. In practice, the viscosity of the concrete can be measured by the flow time of a given volume of concrete through a frustoconical cone. The shorter the flow time, the less viscous concrete is and easier to install. It is thus common to add water to the concrete during transport from the manufacturing plant or on the site if it has lost fluidity. However, if the addition of water makes it possible to reduce the viscosity of a concrete formulation, it can also lead to a deterioration of the mechanical strengths and increased risk of cracking, which may give rise to disputes over hardened concrete. The discovery of the exceptional dispersing properties of

Polyalkoxylated polycarboxylate (PCP) comb-poly (co) polymers, also known as superplasticizers, have allowed concrete technology to progress rapidly. However, their water-reducing effect does not presuppose their effect lowering the viscosity of concretes, which is very variable. These superplasticizers are (co) polymers having a comb structure, the main polymer chain of which contains carboxylic groups which carry side chains composed of polyether type sequences.

In order to improve the viscosity-reducing capacity of PCP additives, patent application WO 2004/099100 describes mixtures of (co) polymers, one of which has been modified by introduction of a hydrophobic group into the side chain. These (co) polymer blends are however quite complex and both their formulation and their properties may be difficult to control.

Moreover, the patent application WO 2004/099099 proposes (co) polymers obtained by polymerization of 20 to 60% by weight of alkyl (meth) acrylate, 15 to 40% by mole of unsaturated monomer carrying a polyalkylene glycol chain. and 19 to 65 mol% of a carboxylic acid. According to this document, only the (co) polymers prepared by respecting these ranges give favorable results.

Patent Application JP 09248438 discloses (co) polymers comprising a main chain, in particular consisting essentially of (meth) acrylic units, and polyoxyalkylated side chains comprising hydrophobic units randomly distributed as an adjuvant in order to lower the viscosity of hydraulic compositions.

An object of the invention was therefore to provide specific adjuvants for improving the viscosity, in particular by reducing it, formulations of hydraulic compositions, while retaining interesting properties of water reduction.

Another aim was finally to propose such additives which are inexpensive and easy to manufacture industrially. This object is achieved by the use of (co) polymers comprising a main chain obtained essentially from (meth) acrylic monomers, and polyoxyalkyl-type side chains comprising hydrophobic units randomly distributed as an adjuvant in order to to lower the viscosity of hydraulic compositions. The invention is based on the surprising finding that the combination, in a (co) polymer, of units derived from (meth) acrylic monomers in the main chain and polyoxyalkyl-type side chains comprising hydrophobic units statistically distributed. accessible by a simple and inexpensive preparation process, gives the polymers an interesting behavior in terms of lowering the viscosity.

As used herein, the term "comb polymer" refers to (co) polymers comprising a main chain and side chains. The term "(co) polymer" embraces polymers and copolymers obtained by polymerization of one or more monomers, respectively.

The term "(meth) acrylic monomers" includes acrylic monomers and methacrylic monomers. The term "hydraulic compositions" means any composition having a hydraulic setting, and especially cements, mortars and concretes for all construction markets (building, civil engineering or prefabrication plant).

The term "hydrophobic group" or "hydrophobic unit" is understood to mean a group having a negative contribution in the calculation of HLB according to the theory of

Davies (J.T. Davies, Proc.Inter Surface Surface Active Substances, 2nd,

London, Vol. I, p. 426 (1957)). The HLB values can for example be the following:

HLB groups according to Davies theory

-OSO ₃ Na +38.7

-COOK +21, 1

-COO Na +19.1

-N ternary amine +9.4

Ester (sorbitan) +6.8

Ester (free) +2,4

-COOH +2.1

-OH (free) +1, 9

-O- +1, 3

-OH (sorbitan) +0.5

-CH ₂ -CH ₂ -O- (ethylene oxide group) +0.33

-CH (CH ₃ ) -CH ₂ -O- (propylene oxide group) -0.015

-CH ₃ , -CH ₂ -, = CH- -0.475

Preferably, the hydrophobic unit comprises or consists of oxyalkylene groups having more than 2 carbon atoms, and most preferably, at least three carbon atoms. Preferably, groups hydrophobic are oxypropylene and oxybutylene groups, preferably oxypropylene groups.

The term "statistical distribution" is intended to mean an irregular distribution, and therefore not a block distribution of the hydrophobic units in the side chain. This type of distribution is obtained in particular by reaction in the presence of different species and its structure will depend in particular on their respective reactivity. This term is supposed to cover in particular the distributions present in the (co) polymers known as gradient ("graded") or tapered

("Tapered") having strings in which the concentration of a unit increases progressively along the string. This term is also intended to cover distributions having a chain termination having at least one non-hydrophobic group, especially an oxyethylene group.

According to the invention, the (co) polymer used has a specific constitution both in the main chain and in the side chains. The (co) polymer used according to the invention comprises a main chain consisting essentially of (meth) acrylic units, and side chains of polyoxyalkyl type comprising from 1 to 80% by weight relative to the dry polymer of hydrophobic units distributed from statistically.

By the term "essentially compounded" is meant a proportion of at least 50%, preferably at least 80% and more preferably at least 95% by weight of monomer relative to the total of monomers. According to a preferred embodiment, the (co) polymer used according to the invention comprises only (meth) acrylic units.

Preferably, the main chain has a degree of polymerization of 15 to 45, especially 20 to 40.

According to one embodiment of the invention, the (meth) acrylic units in the (co) polymer used are of formula (I) below:

in which : R ¹ is hydrogen or methyl;

Z is O or NH; and

R ² is H or an alkyl, aryl, alkylaryl, arylalkyl group of 1 to 20 carbon atoms, or a group -QR ³ in which R ³ is H or an alkyl, aryl, alkylaryl or arylalkyl group of 1 to 20 atoms of carbon, and Q is of formula (II):

in which :

Y ₁ represents an alkylene group of 2 carbon atoms,

Y ₂ represents an alkylene group of 3 carbon atoms; Y ₃ represents an alkylene group of 4 carbon atoms;

n is an integer from 1 to 200;

m is an integer from 0 to 150;

q is an integer from 0 to 150; and

- (n + m + q) is an integer from 1 to 500, wherein the (co) polymer of formula (I) has at least one Q group with m or q> 0.

The word "ran" indexing the brackets in formula (II) means that groups Y ₁ O to Y ₃ O are statistically distributed in group Q.

In the (co) polymer used according to the invention, it is not necessary for each of the groups Q to have groups Y ₂ O or Y ₃ O. However, the average ratio n / (n + m + q) varies from preferably between 0.2 and 0.99.

Preferably, the average molecular weight of the side chains is from 500 to 5000 g / mol.

Preferably, the (co) polymer may be obtained by radical polymerization of a (meth) acrylic monomer of formula (Ia):

in which the substituents R ¹ , Z and R ² have the same meaning as in the formula (I) above.

In formulas (I) (Ia) and (II) above, the following characteristics are particularly preferred:

- Z is O;

- R ² is a group -QR ³ in which:

R ³ represents a methyl or ethyl group, preferably a methyl group; N is an integer ranging from 1 to 150, preferably from 1 to 100;

M is an integer ranging from 1 to 100, preferably from 1 to 75; and

• q is 0;

• the average ratio n / (n + m + q) varies from 0.5 to 0.99. Advantageously, the (co) polymers described may be composed of different units. In particular, it may be advantageous to introduce different side chains in their length and / or the number and arrangement of the hydrophobic units.

Moreover, the (co) polymers described may also comprise other units in the main chain. In particular, it may be advantageous to introduce units derived from maleic monomers, in particular chosen from the group of maleic acid, maleic anhydride, hemi-esters of maleic acid with alcohols, glycols or amines containing 1 to 10 carbon atoms and optionally alkoxylated with 1 to 500 oxyalkylene units. These units may optionally also carry polyoxyalkylated side chains comprising hydrophobic units randomly distributed.

The content of such units in the (co) polymer is, however, preferably less than 35%, and preferably less than 25% by number. Particularly preferred are the polymers whose chain consists of units (meth) acrylics, excluding other units. In the absence of allylic monomer, the percentage of this type of units can be up to 49% by number.

Advantageously, the (co) polymer according to the invention comprises at least 3% of hydrophobic units, preferably at least 17% of hydrophobic units in weight percentage relative to the weight of the (co) polymer.

Preferably, the (co) polymer according to the invention comprises at most 60% of hydrophobic units in weight percentage relative to the weight of the (co) polymer.

According to the invention, the (co) polymer comprises oxyalkylene side chains comprising hydrophobic units randomly distributed in the chain.

The (co) polymers having this type of distribution are particularly easy to prepare, since the polyoxyalkylated chain can be synthesized in a single step, in the presence of the various alkylene oxides, instead of a multi-stage process, such as is most often the case for the preparation of

(co) block polymers, for example.

The oxyalkylene side chain may be present on the monomer (s) as early as before the polymerization or may result from an esterification reaction after polymerization. When the oxyalkylene side chains comprising hydrophobic units are carried by the monomer, the (co) polymers may thus be obtained by copolymerization, preferably of radical type, of appropriate monomers. The (co) polymerization can be carried out by a radical route conventionally as described, for example, in the patent application PCT / FR2005 / 002438.

Alternatively, the side chains can be introduced by reaction of a polycarboxylic acid with a suitable polyether, according to the method described for example in the application FR 2 776 285.

According to one variant, the (co) polymer can be obtained by post-esterification, a process in which, in the presence of water and a catalyst, the reaction is carried out at a temperature of between 120 and 250 ° C. :

at least one polycarboxylic acid obtained by polymerization of at least one unsaturated carboxylic acid; and at least one polyether containing a free hydroxyl group capable of reacting with a carboxylic function of said polycarboxylic acid, the catalyst being an alkaline or alkaline-earth salt of a strong protic acid.

The catalyst may be chosen in particular from alkyl-, alkylaryl-, aryl-, or arylalkylsulfonic acid salts, alkyl-, alkylaryl-, aryl-, or arylalkylphosphoric acids, alkyl-, alkylaryl-, aryl-, or arylalkylphosphonic and alkyl-, alkylaryl-, aryl-, or arylalkyl acid sulphates. The catalyst is an alkaline or alkaline-earth salt of the acids defined above, and notably includes the Na, K, Li, Ca and Mg salts. The catalyst may be added in an amount of from 0.04% to 10% molar, based on the number of carboxylic functions of the polycarboxylic acid.

Preferably, the polycarboxylic acid is obtained by polymerization of monomers containing as essential component (meth) acrylic acid. Optionally, the polycarboxylic acid can also be derived from other comonomers comprising a functionality different from a carboxylic acid with one or more ethylenic unsaturations that can be copolymerized with (meth) acrylic acid, such as maleic acid and the like. maleic anhydride or monomers comprising sulfonic, acidic, phosphoric, phosphonic and vinylmethallyl sulfates. Preferably, the polycarboxylic acid is a homopolymer and / or a

(co) polymers of (meth) acrylic acid or (co) polymer of (meth) acrylic acid and maleic acid or maleic anhydride. The weight average molar mass Mw of the polycarboxylic acid is preferably between 500 and 60,000, especially between 500 and 3800, in particular between 1000 and 3500. The polyether may in particular be a polyalkylene glycol alkyl ether of formula QR ³ wherein R ³ and Q are as indicated for formula (II) described above. This type of macromonomer can be obtained for example by anionic polymerization with several alkylene oxides in the presence of a strong base. For example, 5 to 80 mol% of polyether relative to the number of available carboxylic functions of the polycarboxylic acid are added. Preferably, the polyether consists of: one or more polyethylene glycol alkyl ethers, containing oxypropylene units, distinguished by their weight average molecular weight; or

one or more polypropylene glycol alkyl ethers containing oxyethylene units, differing in their weight average molecular weight, or

a mixture of the alkylethers thus defined.

The average molar mass of the polyether can vary from 150 to 30,000, preferably from 300 to 10,000, in particular from 300 to 5,000, preferably from 500 to 5,000, in particular from 1,000 to 3,000. The amount of polyether used in the The process described will depend on the degree of esterification desired.

The esterification reaction can be carried out so as to esterify a part, for example 5 to 80% of the carboxylic functions with a polyether or a mixture of polyethers. It is generally conducted under reduced pressure to gradually eliminate the water formed during the reaction. The reduced pressure is generally between about 5 and 150 mbar. The reaction is stopped as soon as the target percentage of esterified carboxylic functions of the polycarboxylic acid is reached.

The weight average molecular weight, "Mw", of the dispersant copolymer, measured by gel permeation chromatography with a polyethylene glycol calibration, generally ranges from about 1000 to about 1,000,000, preferably from about 10,000 to about 80,000, in particular from 10,000 to 50,000, in particular from 15,000 to 45,000. Unless otherwise indicated, in the present application, the molar masses are expressed in g / mol, the unit being commonly omitted.

Advantageously, the (co) polymer used according to the invention can be used without subsequent purification. When it has been prepared according to the method described above, the (co) polymer may be used in native form or at a selected level of neutralization using a base or a mixture of bases known to those skilled in the art. , for example sodium hydroxide, lithium hydroxide, potassium hydroxide, calcium hydroxide or a primary, secondary or tertiary amine. The (co) polymer used according to the invention is generally packaged in the form of a solution, in particular an aqueous solution, or in a solvent, as a dispersion, or in the form of a powder. Preferably, it is used in the form of an aqueous solution, for example at a concentration of 20 to 80%, preferably 20 to 40% by dry weight.

In addition, the formulation may further include an antifoam to correct the air ratio of the hydraulic composition. The anti-foam formulation and dosage will depend on the structure of the dispersant polymer and the desired air ratio. The results obtained show that the viscosity reducing effect at 5 minutes is proportional to the amount of hydrophobic groups relative to the binder. Also, the (co) polymer dosage can be adjusted so that the level of hydrophobic groups in the hydraulic binder composition is between 0.02 to 0.5% by weight based on the weight of binder, according to the desired effect.

Finally, the formulated (co) polymer may be used alone or in combination with one or more other additives such as an accelerator, retarder or other dispersant, in order to adjust the rheological and setting properties of the material.

(Co) polymer can be used with hydraulic cement-based compositions such as Portland CEM I cements; aluminous cements, various CEM II or CEM III composite cements consisting of mixing, before or after grinding of Portland clinker and slag, natural pozzolans and / or fly ash; or hydraulic materials other than cement, such as hydraulic calcium sulphates, binders containing CSA (calcium sulphate aluminates), hydraulic glasses, magnesium and phosphatic binders.

The additives described can be used for various hydraulic compositions, including concrete, mortar, grout, screed or paste compositions. The use of the (co) polymers described is particularly advantageous for lowering the viscosity of concrete compositions having an E / C ratio (mass ratio between water and cement) of from 0.15 to 1, preferably from 0.2 to 0.8. They are particularly interesting for self-leveling / self-leveling concrete (BAN / BAP) formulations, ready-to-use concretes, or concretes intended for the field of pre-fabrication.

The invention will be described below in more detail by means of the figures and examples which follow:

Figure 1: a diagram showing the effect of the hydrophobic groups assay on the viscosity at 5 minutes for the acrylic (co) polymers; and

2: a diagram showing the effect of the hydrophobic groups assay on the viscosity at 5 minutes for methacrylic (co) polymers.

EXAMPLES

Unless otherwise indicated, the percentages are given in the following statement by weight relative to the weight of the final formulation.

EXAMPLE A (comparison example)

In a quadricol equipped with a stirrer and heating means and connected to a water pump, 25 g of polyacrylic acid were introduced (Mw = 2000, measured acid titer = 330 mg KOH / g, dry extract 49% by weight). weight) and then 0.34 g (5.5 mol% of the carboxylic functions of polyacrylic acid) of lithium hydroxide. In the medium were then introduced 73.66 g (25 mol% of the carboxylic functions of polyacrylic acid) methylene polyethylene oxide molar mass Mw 2000 (MPEG2000). The reaction mixture was brought to a temperature of 80 ° C. and gradually put under vacuum (pressure of approximately 50 mbar). At the end of the distillation of the water, the temperature of the reaction medium was brought gradually to 175 ° C. The reaction time was measured from the moment when the reaction medium reached 170 ° C. The reaction was continued for a period of 6 hours. The progress of the esterification reaction is followed by the dosage of

Unreacted MPEG, by GPC, by comparing the peak area with a previously established calibration curve. The residual polyether content is shown in Table 1 below At the end of the reaction, the reaction medium is brought back to atmospheric pressure and the heating is cut off. Once the temperature of the reaction medium is lower than 90 ° C., the molten polymer is diluted to 50% by weight in water.

EXAMPLE B (example of comparison)

In a quadricol equipped with a stirrer and heating means and connected to a water tube, 25.0 g of polymethacrylic acid (Mw = 4000, ie a degree of polymerization of the main chain of about 47, was introduced, measured acid titer = 184.8 mg KOH / g, dry extract 30.4% by weight) then 2.0 g (2.5 mol% of the carboxylic functions of polymethacrylic acid) of a solution of sodium hydroxide with 50% by weight.

In the medium were then introduced 30.1 g (18.25 mol% of the carboxylic functions of polymethacrylic acid) ethylene oxide methoxylated molar mass Mw 2000 (MPEG 2000) and 11.3 g 18.25% molar carboxylic functions of polymethacrylic acid) of ethoxylated polyethylene oxide of molecular weight Mw 750 (MPEG 750).

The reaction mixture was brought to a temperature of 80 ° C. and gradually put under vacuum (pressure of approximately 50 mbar). At the end of the distillation of the water, the temperature of the reaction medium was gradually raised to

175 ° C. The reaction time was measured from the moment when the reaction medium reached 170 ° C. The reaction was continued for a period of

8:30. The residual polyether content is shown in Table 1 below.

At the end of the reaction, the reaction medium is brought back to atmospheric pressure and the heating is cut off. Once the temperature of the reaction medium is lower than 90 ° C., the molten polymer is diluted to 50% by weight in water.

EXAMPLE C (Comparison Example) In a quadricol equipped with an agitator and heating means and connected to a water tube, 50 g of polymethacrylic acid (Mw = 4000, ie a degree of polymerization of the chain) were introduced. of about 47, measured acid titer = 184.8 mg KOH / g, dry extract 30% by weight) then 0.34 g (2.5 mol% of carboxylic functions of polymethacrylic acid) of a solution of sodium hydroxide at 50% by weight.

In the medium were then introduced 95.76 g (29 mol% of the carboxylic functions of polymethacrylic acid) ethylene oxide methoxylated molar mass Mw 2000 (MPEG2000) containing 20 mol% of propylene oxide statistically distributed on along the chain, which is terminated by a methoxy group. The reaction mixture was brought to a temperature of

80 ° C and gradually put under vacuum (pressure of about 50 mbar). At the end of the distillation of the water, the temperature of the reaction medium was brought gradually to 175 ° C. The reaction time was measured from the moment when the reaction medium reached 170 ° C. The reaction was continued for a period of 6 hours.

The progress of the esterification reaction is followed by the assay of unreacted MPEG, by GPC, by comparing the area of the peak with a previously established calibration curve. The residual polyether content is shown in Table 1 below

EXAMPLE D (example of comparison)

In a quadricol equipped with a stirrer and heating means and connected to a water tube, 50 g of polymethacrylic acid (Mw = 4000, ie a degree of polymerization of the main chain of about 47, was introduced. measured acid = 184.8 mg KOH / g, dry extract 30% by weight) then 0.34 g (2.5 mol% of the carboxylic functions of polymethacrylic acid) of a solution of 50% sodium hydroxide in weight.

In the medium were then introduced 102.31 g (31 mol% of the carboxylic functions of polymethacrylic acid) ethylene oxide methoxylated molar mass MW 2000 (MPEG2000) containing 10 mol% of propylene oxide statistically distributed on along the chain, which is terminated by a methoxy group. The reaction mixture was brought to a temperature of 80 ° C and gradually put under vacuum (pressure of about 50 mbar). At the end of the distillation of the water, the temperature of the reaction medium was brought gradually to 175 ° C. The reaction time was measured from the moment when the reaction medium reached 170 ° C. The reaction was continued for a period of 6 hours.

The progress of the esterification reaction is followed by the assay of unreacted MPEG, by GPC, by comparing the area of the peak with a previously established calibration curve. The residual polyether content is indicated in Table 1 below. At the end of the reaction, the reaction medium is brought back to atmospheric pressure and the heating is stopped. Once the temperature of the reaction medium is lower than 90 ° C., the molten polymer is diluted to 50% by weight in water.

EXAMPLE 1

In a quadricol equipped with a stirrer and heating means and connected to a water pump, 25 g of polyacrylic acid (Mw = 2000, ie a degree of polymerization of the main chain of about 28, acidic title) was introduced. measured

= 330 mg KOH / g, dry extract 49% by weight) then 0.34 g (5.5 mol% of the carboxylic functions of polyacrylic acid) of lithium hydroxide.

73.66 g (25 mol% of the carboxylic functions of polyacrylic acid) of polyether (polyethylene oxide / polypropylene oxide of molar mass MW 2000 containing 10 mol% of propylene oxide, statistically distributed) were then introduced into the medium. along the chain, which is terminated by a methoxy group).

8:30. The residual polyether content is shown in Table 1 below.

At the end of the reaction, the reaction medium is brought back to atmospheric pressure and the heating is cut off. Once the temperature of the environment When the reaction temperature is below 90 ° C., the molten polymer is diluted to 50% by weight in water.

Table 1: constitution of the (co) polymers tested

^* on average, the polyether has chains with 50% and 0% OP

EXAMPLE 2

Example 1 was repeated under the same operating conditions but replacing the polyether with an MPEG of molar mass 2000 with 20 mol% of oxypropylene units. The reaction is stopped after 8:30. The residual polyether content is shown in Table 1 above. EXAMPLE 3

The catalyst solution was first prepared by neutralization of p-toluenesulphonic acid in aqueous solution, the pH of which was brought to a pH of between 7 and 10 using sodium hydroxide (at 50%, then 1N). and finally 0.1 N).

In a quadricol equipped with a stirrer and heating means and connected to a water pump, 25 g of polyacrylic acid were introduced (Mw = 2000, measured acid titer = 330 mg KOH / g, dry extract 49% by weight). weight) then 0.86 g (28.7 g of a 3% by weight solution, 3 mol% of the carboxylic functions of polyacrylic acid) of sodium p-toluenesulphonate.

In the medium were then introduced 73.66 g (25 mol% of the carboxylic functions of polyacrylic acid) polyethylene oxide / polypropylene oxide of molar mass Mw 2000 containing 50 mol% of propylene oxide statistically distributed along of the chain, which is terminated by a methoxy group.

The reaction mixture was brought to a temperature of 80 ° C. and gradually put under vacuum (pressure of approximately 50 mbar). At the end of the distillation of the water, the temperature of the reaction medium was brought gradually to 175 ° C. The reaction time was measured from the moment when the reaction medium reached 170 ° C. The reaction was continued for a period of 8:30.

The progress of the esterification reaction is followed by the measurement of MPEG (unreacted methoxy terminated polyether), by GPC, by comparing the area of the peak with a previously established calibration curve. At the end of the reaction, the reaction medium is brought back to atmospheric pressure and the heating is cut off. Once the temperature of the reaction medium is lower than 90 ° C., the molten polymer is diluted to 50% by weight in water.

The residual polyether content is shown in Table 1 above.

EXAMPLE 4

In order to study the influence of the arrangement of the hydrophobic groups, Example 1 was repeated under the operating conditions of Example 3 but in replacing the polyether with a mixed MPEG OP / OE of the same molar mass comprising a chain with a molar ratio OP / (OE + OP) of 50% and a chain 100% of oxyethylene units. Given the proportion between the two chains, the MPEG comprises on average 10 mol% of oxypropylene units per chain. The reaction is stopped after 6 hours. The residual polyether content is shown in Table 1 above.

EXAMPLE 5

In a quadricol equipped with a stirrer and heating means and connected to a water tube, [25.0] g of polymethacrylic acid (Mw = 4000, measured acid titer = 184.8 mg KOH / g, dry extract 30.4% by weight) then 2.0 g (2.5 mol% of the carboxylic functions of polymethacrylic acid) of a solution of sodium hydroxide at 50% by weight.

In the medium were then introduced 30.1 g (18.5 mol% of the carboxylic functions of polymethacrylic acid) of polyethylene oxide / polypropylene oxide of molar mass Mw 2000 containing 10 mol% of propylene oxide distributed statistically along the chain, which is terminated by a methoxy group and 1 1, 3 g (18.5 mol% of the carboxylic functions of polymethacrylic acid) ethylene oxide methoxylated molar mass MW 750 (MPEG750).

The reaction mixture was brought to a temperature of 80 ° C. and gradually put under vacuum (pressure of approximately 50 mbar). At the end of the distillation of the water, the temperature of the reaction medium was brought gradually to 175 ° C. The reaction time was measured from the moment when the reaction medium reached 170 ° C. The reaction was continued for a period of 8:30. At the end of the reaction, the reaction medium is brought back to atmospheric pressure and the heating is cut off. Once the temperature of the reaction medium is lower than 90 ° C., the molten polymer is diluted to 50% by weight in water. The residual polyether content measured is shown in Table 1 below. EXAMPLE 6

Example 5 is repeated under the same operating conditions but replacing the molar mass polyether Mw 2000 with a polyethylene oxide / polypropylene oxide of molar mass Mw 2000 containing 30 mol% of propylene oxide distributed statistically along the chain, which is terminated by a methoxy group. The reaction is stopped after 8:30 h. The residual polyether content measured is shown in Table 1 above.

EXAMPLE 7

Example 5 is repeated under the same operating conditions but replacing the molar mass polyether Mw 2000 with a polyethylene oxide / propylene oxide of molar mass Mw 2000 containing 50 mol% of propylene oxide distributed statistically along the chain, which is terminated by a methoxy group. The reaction is stopped after 8:30. The residual polyether content measured is shown in Table 1 above.

EXAMPLE 8 Example 8 is similar to Example C except that polymethacrylic acid (Mw = 4000) is replaced by polymethacrylic acid of molar mass Mw of 3100 g / mol, which corresponds to a degree of polymerization of about 35.

More specifically, in a quadricol equipped with a stirrer and heating means and connected to a water pump, was introduced 50 g of polymethacrylic acid (Mw = 3100, measured acid titer = 166 mg KOH / g, extract dry 30% by weight) then 0.32 g (2.5 mol% of the carboxylic functions of polymethacrylic acid) of a solution of sodium hydroxide at 50% by weight.

In the medium were then introduced 86.01 g (29 mol% of the carboxylic functions of polymethacrylic acid) methylene polyethylene oxide molar mass Mw 2000 containing 20 mol% of propylene oxide statistically distributed along the chain, which is terminated by a methoxy group. The reaction mixture was brought to a temperature of 80 ° C. and gradually put under vacuum (pressure of approximately 50 mbar). At the end of the distillation of the water, the temperature of the reaction medium was gradually raised to

8:30. At the end of the reaction, the reaction medium is brought back to atmospheric pressure and the heating is cut off. Once the temperature of the reaction medium is lower than 90 ° C., the molten polymer is diluted to 50% by weight in water. The residual polyether content measured is shown in Table 1 above.

EXAMPLE 9

Example 8 is repeated under the same operating conditions but replacing the molar mass polyether Mw 2000 with an ethylene oxide / polypropylene oxide of molar mass Mw 2000 containing 10 mol% of propylene oxide distributed statistically along the chain, which is terminated by a methoxy group. The reaction is stopped after 8:30 h. The residual polyether content measured is shown in Table 1 above.

EXAMPLE 10

Example 8 is repeated under the same operating conditions but replacing the molar mass polyether Mw 2000 with an ethylene oxide / propylene oxide polyoxide of molar mass Mw 2000 containing 30 mol% of propylene oxide distributed statistically along the chain, which is terminated by a methoxy group. The reaction is stopped after 8:30. The residual polyether content measured is shown in Table 1 above.

EXAMPLES OF APPLICATION

The polymers obtained in Examples 1 to 10 were tested as additives for various hydraulic compositions and compared to those of polymers according to Examples A, B, C and D.

Unless otherwise indicated, the polymers are used without subsequent purification, as obtained at the end of the reaction, after neutralization and dilution to 20% by weight in aqueous solution.

The performance of the polymers as adjuvants of hydraulic compositions are evaluated by following the viscosity and the spreading of test mortars.

Two different mortar formulations were used, which will later be called Mortar I and Mortar II. Their composition is shown in Table 2 below.

Table 2: Composition of mortars I and II

The cement is CEM I 52.5 from Saint Pierre La Cour (Supplier: Lafarge).

The respective dosages of adjuvants indicated in Table 3 are expressed in dry weight relative to the amount of cement.

The mortar was prepared at hygrometry and constant temperature (20 ± 1 ° C - 70 ± 5% relative humidity).

In order to neutralize a possible foaming effect of the adjuvants, a dose of tributylphosphate (1% relative to the adjuvant solution) is added together with the (co) polymer in the mixing water. a) Preparation of the mortar

The mortar was prepared as follows:

In the bowl of a mixer (Perrier BA 008) was introduced the standardized sand. Then, about 6% w / w of wetting water sand was added by mixing at about 140 rpm in 30 seconds. The mixture was continued for 30 seconds before allowing the mass to stand for 4 minutes. Then, the cement and the calcareous filler (Origin: ERBRAY supplied by the company MEAC) were introduced and kneaded for 1 minute before adding the mixing water and the specified dosage of adjuvant, while mixing. After these steps, mixing was continued for another 2 minutes at 280 rpm.

b) Fluidizing and viscosity reducing effect The fluidizing effect and the viscosity reducing effect were measured by means of micro-concrete tests.

The fluidizing effect is evaluated by measuring the spreading of a mortar on a glass plate.

The amount of adjuvant is dosed so as to obtain sufficient initial fluidification, that is to say a spreading value of 320 to 350 mm. The initial dosage is indicated in% by weight (of dry polymer) relative to the weight of cement.

The initial deadline is 5 minutes after adding the cement to the wet sand mix.

The viscosity is also evaluated by measuring the flow time of the mortar through a frustoconical funnel, having a diameter of 150 mm at the base and 17 mm at the top, and having two marks separated by 60 mm, the first 12 mm from the base.

The viscosity of the mortar corresponds to the value in seconds of the time required for the mortar to flow through the funnel of mark 1 to mark 2.

The viscosity reducing effect of an adjuvant is found by comparing the viscosity values of the micro-concretes for comparable spreading. Table 3: Effects of Acrylic Polymers on the Viscosity of Test Mortars (Mortar I)

: in% in dry weight / weight of cement

It is found that the substitution of oxyethylene groups in the side chains of PCP-type polymers based on acrylic monomers with hydrophobic oxypropylene groups makes it possible to reduce the viscosity of mortar formulations. Indeed, it is found that even a small presence of hydrophobic groups has a noticeable effect on the reduction of the viscosity. Thus, the adjuvant according to Example A not containing propylene oxide shows a higher flow value than Examples 1 to 4 which contain hydrophobic groups, namely propylene oxide links. The presence of 50% of oxypropylene groups in the polymer according to Example 3 makes it possible to lower the dosage while allowing a reduction in the viscosity.

The polymer according to example 4 makes it possible to judge the effect of the arrangement of the hydrophobic groups in the polymer, since it comprises side chains having 50% oxypropylene units and side chains consisting only of oxyethylene. There is also a significant decrease in the initial viscosity. So it seems to be the overall group content.

Table 4: Effects of methacrylic polymers on viscosity - CEM I SPLC (mortar II)

It is found that the substitution of oxyethylene groups in the chains Side effects of the PCP type polymers based on methacrylic monomers with hydrophobic oxypropylene groups makes it possible to reduce the viscosity of mortar formulations.

Figures 1 and 2 show that the viscosity reducing effect is related to the amount of hydrophobic groups introduced into the binder batch, both for (co) acrylic polymers and for (co) polymers methyacrylic. Indeed, it is found that in the range studied, the drop in viscosity is proportional to the product of the assay and the content of hydrophobic groups of the (co) polymer.

Table 5: Effects of degree of polymerization of the main chain

^* : in% in dry weight / weight of cement

It is found that the decrease in the degree of polymerization of the main chain of the dispersant copolymer makes it possible to reduce the viscosity of mortar formulations. In Examples 8, 9 and 10 relating to a copolymer whose main chain has a degree of polymerization of 35, the viscosity reduction obtained is approximately 20% relative to Examples C and D for which the main chain of the copolymer has A degree of polymerization of 47. In addition, in addition to providing a similar 5 minute spread and a decrease in viscosity, the copolymer whose main chain has a degree of polymerization of 35 is used with a dosage of about 16% lower than the dosage of the copolymer whose main chain has a degree of polymerization of 47.

Claims

1. Use of a (co) polymer having a main chain consisting essentially of (meth) acrylic units and polyoxyalkyl-type side chains comprising hydrophobic units randomly distributed as an adjuvant in order to lower the viscosity of hydraulic compositions.

2. Use according to claim 1, wherein the main chain has a degree of polymerization of 15 to 45.

3. Use according to claim 1 or 2, wherein the average molecular weight of the side chains is from 500 to 5000 g / mol.

4. Use according to any one of claims 1 to 3, wherein the weight average molar mass of the (co) polymer is 10,000 to 50,000 g / mol.

5. Use according to any one of claims 1 to 4, wherein:

the main chain has a degree of polymerization of 15 to 45,

the average molecular weight of the side chains is from 500 to 5000 g / mol, and the weight average molar mass of the (co) polymer is from 10,000 to 50,000 g / mol.

Use of (co) polymers according to any one of claims 1 to 5, wherein the hydrophobic units are oxypropylene and oxybutylene groups.

The use of claim 6, wherein the hydrophobic units are oxypropylene groups.

8. Use according to one of claims 1 to 7, wherein the (co) polymer comprises (meth) acrylic units of formula (I) below:

in which :

R ¹ is hydrogen or methyl;

Z is O or NH; and

ran

(H) wherein:

Y ₁ represents an alkylene group of 2 carbon atoms,

Y ₂ represents an alkylene group of 3 carbon atoms;

Y ₃ represents an alkylene group of 4 carbon atoms;

n is an integer from 1 to 200;

m is an integer from 0 to 150;

q is an integer from 0 to 150; and

9. Use according to claim 8, wherein the (co) polymer is obtainable by radical polymerization of a (meth) acrylic monomer of formula (la):

wherein the substituents R ¹ , Z and R ² have the same meaning as for formula (I) in claim 8.

10. Use according to one of claims 8 or 9, wherein in formulas (I) and (la), Z is an oxygen.

1. Use according to one of claims 8 to 10, wherein in the formulas (I) and (la), R ² is a group -QR ³ in which R ³ is a methyl or ethyl group.

12. Use according to one of claims 8 to 11, wherein in the formula (II), R ² is a group -QR ³ in which n ranges from 1 to 100 and m varies from 1 to 75 and q is 0.

13. Use according to one of claims 1 to 12, wherein the (co) polymer dosage is adjusted so that the level of hydrophobic groups in the hydraulic binder composition is between 0.02 to 0.5 % by weight relative to the weight of binder.

14. Use according to one of claims 1, 6 and 8 to 12, wherein the (co) polymer is obtainable by a process in which is reacted in the presence of water and a catalyst, at a temperature of between 120 and 250 ° C: at least one polycarboxylic acid obtained by polymerization of at least one unsaturated carboxylic acid; and at least one polyether containing a free hydroxyl group capable of reacting with a carboxylic function of said polycarboxylic acid, the catalyst being an alkaline or alkaline-earth salt of a strong protic acid.